二溴苯物系固液平衡测定与正规溶液模型

采用差示扫描量热法测定了邻二溴苯与间二溴苯、对二溴苯与间二溴苯和对二溴苯与邻二溴苯的3个二元固液平衡数据,同时绘制出相应的简单低共熔型二元相图。各物系低共熔摩尔分数组成和温度分别为：邻二溴苯(x) 间二溴苯(1-x),x=0.4485,t=240．4K;对二溴苯(x) 间二溴苯(1-x),x=0.1002,T=260.9K：对二溴苯(x) 邻二溴苯(1—x),x=0.1306,T=272.3K。采用单参数正规溶液模型计算,温度均方根偏差不大于1.1K,说明正规溶液模型适用于上述弱极性异构体物系固液平衡计算．     

邻-间-对苯二酚固液平衡测定与关联

采用差示扫描量热法测定了邻苯二酚与间苯二酚、邻苯二酚与对苯二酚、间苯二酚与对苯二酚二元固液平衡数据,同时绘制出相应的简单低共熔型二元相图。低共熔组成和温度为：邻苯二酚(1) 间苯二酚(2),x1=0.5077,336.3K;邻苯二酚(1) 对苯二酚(3),x1=0.7879,365.8K;对苯二酚(3) 间苯二酚(2),x3=0.2305,366.1K。采用Wilson方程关联,标准偏差分别为0.48K,0.48K和0.56K。     

4-羟基苯甲醛及其溴代物三元固液平衡

采用差热扫描量热法,通过对一系列“拟二元”物系固液平衡的测定,得到了4-羟基苯甲醛、3-溴-4-羟基苯甲醛和3,5-二溴-4-羟基苯甲醛物系的三元固液平衡数据,实验结果表明本物系为简单低共熔型,其低共熔摩尔组成和温度分别为：3,5-二溴-4-羟基苯甲醛（x₁）＋3-溴-4-羟基苯甲醛（x₂）＋4-羟基苯甲醛（x₃）,x₁=0.2445,x₂=0.3883,x₃=0.3672,T_eu＝338.5 K。同时绘制出相应三元相图,并采用Ott方程对实验数据进行了很好的关联;根据Wilson方程由二元溶液的相互作用参数,对本物系进行计算,关于温度的标准偏差为0.97 K,计算值和实验值符合良好,说明Wilson方程能较好地描述文中三元固液平衡体系。     

2,3-2,5-2,6-二甲基苯酚常压固液相平衡的测定及关联

为了探索采用熔融结晶分离二甲基苯酚系列同分异构体的可行性,并为后续的熔融结晶机理、动力学研究及工艺开发提供数据支撑,采用差示扫描量热法测定了2,3-2,5-2,6-二甲基苯酚(DMP)3个二元体系的固液相平衡数据,结果表明:2,3-2,5-DMP,2,3-2,6-DMP,2,5-2,6-DMP 3个二元体系的相图均属于...     

4-羟基苯甲醛及其溴代物固液平衡数据测定与关联

引　言香兰素 (vanillin) ,即 3 甲氧基 4 羟基苯甲醛 ,是一种广谱型香料 ,广泛应用于食品、化妆品等行业 ,需求日益增长 .近年来提出的以 4 羟基苯甲醛 (以下简称对醛或Ⅰ )为原料 ,经溴化、甲氧基化人工合成香兰素的新工艺[1～ 3 ] ,越来越受到人们的重视 .溴化反应是该工     

二组分固-液平衡相图在矿物结晶中的应用

主要介绍了二组分固-液平衡相图在岩浆形成矿物过程中的应用,列举了简单低共熔、有化合物生成和有固溶体生成的三种类型的固-液平衡相图应用实例,最后分析解释复杂相图,为提高学生对基础相图知识掌握和运用能力提供素材.     

水-醋酸-二异丙醚三元体系液液相平衡数据的测定

实验测定了水-醋酸-二异丙醚三元体系在293.15 K、303.15 K的液液相平衡数据.分别采用Othmer-Tobias和Bachman方程对实验数据进行了可靠性检验,相关性系数均大于0.983.绘制了三元液液平衡相图.     

水-异丙醚-对苯二酚液-液-固等温平衡数据的实验测定

用气相色谱仪测定了常压下水-二异丙基醚-对苯二酚在50℃和46℃的两个等温平衡数据.这两个等温截面的特点是:存在单相液体与对苯二酚固体的平衡区域,同时存在液相分层的广阔的两相共存区域.实验表明,等温截面上没有液-液-固三相共存点.实验数据包括对苯二酚的饱和溶解度数据和两液相共存数据.二异丙基醚萃取水中对苯二酚的饱和分配系数仅为0.7～1.3,远小于二异丙基醚萃取水中苯酚的分配系数.结论是:等温下用二异丙基醚萃取水中对苯二酚并不很有效.     

合成硝基麝香三元体系的固液平衡

通过试验测定了合成硝基麝香二元体系的固液平衡数据,回归并修正了UNIFAC模型的相互作用参数,使UNIFAC模型具有更高的预测功能;为了评价修正后的UNIFAC模型对合成硝基麝香三元体系的预测功能,利用试验测定的溶解度数据和修正后的UNIFAC模型计算值进行了比较,结果表明相互作用参数的修正是理想的.     

十二烷基苯磺酸钠-异丙醇-水固液平衡实验数据测定及关联

测定了十二烷基苯磺酸钠 (SDBS)于不同温度下在异丙醇 (C3H7OH)和水 (H2 O)的混合溶剂中的溶解度 ,并考察了水中氢氧化钠 (Na OH)含量对 SDBS溶解度的影响。同时绘制出三元相图 ,并利用推导的溶解度模型对固液平衡数据进行关联 ,结果良好     

Solid-Liquid Equilibria of Several Binary and Ternary Systems Containing Maleic Anhydride

Solid-liquid equilibria (SLE) of three binary systems and seven ternary systems containing maleic an-hydride(MA) are measured by visual method. The experimental data are compared with the calculated ones with modified universal quasichemical functional group activity coefficient(UNIFAC) method in which the interaction parameters between groups come from two sources, dortmund data bank(DDB), if there's any, and correlations based on our former presented experimental SLE data of twenty binary systems. New groups of MA, ACCOO group, COO group, >C=O group and cy-CH2 group are defined and the SLE data of rnaleic anhydride in isopropyl acetate in literature are cited in order to assess the new interaction parameters, correlated with Wilson equation and the λh equation. The modified UNIFAC method with these new regressed interaction parameters is also used to predict other three binary systems containing rnaleic anhydride.     

硝基氯苯体系固液平衡研究

利用差式扫描量热法,测定了硝基氯苯同分异构体二元及三元固液平衡 t—x关系。同时,利用表征分子特征的拓扑指标θ关联溶液的过量自由能 G~E。计算了二元及三元硝基氟苯同分异构体的固液平衡。G~E 方程式为G~E=RT 式中 k_(ij)为通过实验确定的两分子相互作用参数。上式计算值与实验值的偏差小于2K。     

Effects of salts in the Hofmeister series and solvent isotopes on the gelation mechanisms for hydroxypropylmethylcellulose hydrogels

The effects of various inorganic salts and isotopic solvents on the thermal gelation behavior of hydroxypropylmethylcellulose (HPMC) in aqueous solutions were examined by micro-differential scanning calorimetry and rheological measurements. It was found that salting-out salts, such as NaCl, promoted the sol–gel transition of HPMC at a lower temperature. An analysis of solvent isotope effects on the changes in the temperature at maximum heat capacity (T_m) with salt concentration showed that interchain hydrogen bonding (hydrogen bonding between the hydroxyl groups of different HPMC chains) was involved in the sol–gel transition, and its strength depended on the temperature and salt concentration. It was demonstrated that the effectiveness of anionic species in changing the T_m of the HPMC solutions was in the sequence of the Hofmeister series. Anionic species play a role in reducing T_m by their influence on the structure of the water, which in turn affects interactions between hydroxyl groups and water molecules, interchain hydrogen bonding, and the strength of the water cages prohibiting hydrophobic association. Rheological and microcalorimetric results indicated that the change in the thermodynamics of gelation of the HPMC aqueous solution was determined by the salt types and concentration, and the effect of monovalent salts was found to be more cooperative than that of multivalent salts on the sol–gel transition. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of poly(styrene‐co‐maleic anhydride) imidization on the miscibility and phase‐separation temperatures of poly(styrene‐co‐maleic anhydride)/poly(vinyl methyl ether) and poly(styrene‐co‐maleic anhydride)/ poly(methyl methacrylate) blends

The objective of this work was to study the miscibility and phase‐separation temperatures of poly(styrene‐co‐maleic anhydride) (SMA)/poly(vinyl methyl ether) (PVME) and SMA/poly(methyl methacrylate) (PMMA) blends with differential scanning calorimetry and small‐angle light scattering techniques. We focused on the effect of SMA partial imidization with aniline on the miscibility and phase‐separation temperatures of these blends. The SMA imidization reaction led to a partially imidized styrene N‐phenyl succinimide copolymer (SMI) with a degree of conversion of 49% and a decomposition temperature higher than that of SMA by about 20°C. We observed that both SMI/PVME and SMI/PMMA blends had lower critical solution temperature behavior. The imidization of SMA increased the phase‐separation temperature of the SMA/PVME blend and decreased that of the SMA/PMMA blend. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Differential Scanning Calorimetry Study of Blends of Poly(ethylene glycol) with Selected Fatty Acids

A series of blends of poly(ethylene glycol) (PEG) with different molecular weights with: (i) capric, (ii) lauric, (iii) myristic, (iv) palmitic or (v) stearic acid, as a thermal energy storage material, has been investigated by differential scanning calorimetry (DSC). Transition temperatures and latent heat of transition of PEG, fatty acids and their binary blends were determined since these properties are of primary importance in the design of phase change energy storage materials. The experimental results showed that it is possible to obtain homogeneous (as indicated by DSC data) polymer/fatty acid blends by mixing in the melt and subsequent solidification. The melting ranges of PEG/fatty acid systems were observed to be from 30 to 72 °C while their heat of transition lies in the range of 168–208 J · g^?1. Synergistic action of the components was found for PEG 10 000/stearic acid blend – heat of transition was ca. 15 and 35% higher than for pure stearic acid and PEG, respectively. This phenomena may be explained in terms of strengthened specific interactions via hydrogen bonding leading to formation of more perfect crystalline lattice.

DSC melting and freezing curves of blends PEG/lauric acid. 1 ‐ PEG 3 400/lauric acid, 2 ‐ PEG 10 000/lauric acid, 3 ‐ PEG 20 000/lauric acid, 4 ‐ PEG 35 000/lauric acid (cooling ‐ 10 K · min^?1), 5 ‐ PEG 3 400/lauric acid, 6 ‐ PEG 10 000/lauric acid, 7 ‐ PEG 20 000/lauric acid, 8 ‐ PEG 35 000/lauric acid (heating ‐ 10 K · min^?1).     

Model free kinetics coupled with finite element method for curing simulation of thermosetting epoxy resins

A finite element method algorithm for epoxy curing degree simulation was developed in Abaqus by integrating the discretized analytical solution of the model free kinetics into its user subroutines. This method was verified by nonisothermal and isothermal DSC experiments of an epoxy resin. By means of this method, the real manufacturing press cycle could be simulated regarding temperature distribution and curing degree with advanced curing degree‐dependent material properties. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46408.     

Determination of the crystalline phases of poly(vinylidene fluoride) under different preparation conditions using differential scanning calorimetry and infrared spectroscopy

A method with good precision has been developed to quantitatively measure the degree of α‐, β‐, and γ crystallinity in poly(vinylidene fluoride) (PVDF) by means of infrared spectroscopy. The phase composition of solution‐deposited PVDF films was found to be strongly influenced by the presence of hydrophilic residues on the silicon substrate, the relative humidity present at film deposition, the spatial position on the substrate, and the thermal treatment of the deposited film. Films produced on pristine surfaces gave predominantly α‐phase PVDF, but when a layer of polar solvent (acetone or methanol) remained on the surface, the films produced were predominantly γ phase. Higher humidity promoted a higher fraction of γ crystallinity in the solution‐deposited PVDF films. Solution‐cast films had highly variable composition across the substrate, whereas spin‐cast films were uniform. High‐temperature annealing of PVDF films normally converts the polymer to the γ phase, but annealing the film while still attached to the silicon substrate inhibited this phase transformation. Low‐temperature annealing of freestanding films led to a previously unreported thermal event in the DSC, a premelting process that is a kinetic event, assigned to a crystalline relaxation. Higher‐temperature annealing gave a double endotherm, assigned to melting of different‐sized crystalline domains. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1093–1100, 2003     

Rheological and thermal properties of poly(ethylene oxide)/multiwall carbon nanotube composites

Poly(ethylene oxide) (PEO) based nanocomposites were prepared by the dispersion of multiwall carbon nanotubes (MWCNTs) in aqueous solution. MWCNTs were added up to 4 wt % of the PEO matrix. The dynamic viscoelastic behavior of the PEO/MWCNT nanocomposites was assessed with a strain‐controlled parallel‐plate rheometer. Prominent increases in the shear viscosity and storage modulus of the nanocomposites were found with increasing MWCNT content. Dynamic and isothermal differential scanning calorimetry studies indicated a significant decrease in the crystallization temperature as a result of the incorporation of MWCNTs; these composites can find applications as crystallizable switching components for shape‐memory polymer systems with adjustable switching temperatures. The solid‐state, direct‐current conductivity was also enhanced by the incorporation of MWCNTs. The dispersion level of the MWCNTs was investigated with scanning electron microscopy. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008